Testicular Carcinoid : Microscopic
Microscopic Features of Well-differentiated Neuroendocrine Tumor of the Testis (WDNET; previously known as carcinoid): The microscopic appearance is typical of mid-gut carcinoids. Tumor cells are uniform with eosinophilic granular cytoplasm and regular round nuclei with salt-and-pepper chromatin. The cells are arranged in a variety of patterns, including well-defined solid nests, acinar structures, anastomosing ribbons and cords, trabeculae, and solid sheets. The background stroma is fibrous or hyalinized and tends to retract from the cell nests. Vascular invasion or extratesticular extension is seen in 20% of cases. There is no germ cell neoplasia-in-situ in the surrounding testicular parenchyma.